Screw driver



May 30, 1939.

M. A. WEST SCREW DRIVER Original Filed Dec. 12, 1935 kao L3;

W 9 rm 4 -%Z'5 ATTORNEYS ll my I Patented May 30, 1939 UNITED s'rA'rE 2,160,244 SCREW DRIVER Maxwell A. wee, Portland,

West Screw Corporation,

corporation of Oregon Original application December 12, 1935, Serial No. 54,100; Divided and tember 19, 1936, Serial No.

September 29, 1938 8 Claims.

This inventionrelates to screw drivers, and more particularly, to the portions of the driver which cooperate with the head of a screw and by means of which the driver engages and vide cooperating portions of the character described of improved and more efiicient construction. Another driving portions on the driver bit capable of being more readily engaged and maintained in engagement with the driving portions of the head of the screw during operation of the driver.

Another object of the invention is to so construct the portions of the driver which are in-.

tended to engage thejhead of the'screw as to facilitate cooperation between the head and said portions whereby to' insure the application of a greater turning force without danger of disengaging or damaging the cooperating portions of the driver and the screw.

Another object of the invention is to provide portions on the driver for cooperation with the head of the screw, so constructed that they may .be employed to effectively direct and control the position of the screw.

. Another object of the invention is to provide such a construction of the above parts as will afford maximum strength to the cooperating portions of the driver and the screw.

To these and other ends the invention resides in certain improvements and combinations of parts, all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

In the drawing: V

Fig. 1 is a view illustrating a screw driver embodying the present invention;

Fig. 2 is a side elevation, partly in section, showing a screw and the application thereto of a driver embodying the invention;

turns the screw, one object of the invention being to proreg., assignor to Portland, 0reg., a

this application Sep- 101,623. Renewed object of the invention is to provide Fig. 3 is a sectional view of the screw head as shown in Fig. 2, with the driver removed;

Fig. t is a top plan view of the screw head;

Fig. 5 is a side elevation similar to Fig. 2, but in a plane at right angles thereto;

Fig. 5 is a sectional view of the screw head as shown in Fig. 5, with the driver removed;

Fig. '7 is a sectional elevation on the line Tim-la of Fig. 2.

Fig. 8 is a plan view partly in section on line zld-8a of Fig. 2, showing the screw driver in active or turning relation to the screw, and 3 Fig. 9 is a sectional view of a modification in which the side walls of the wings of the driver preferably tapered are slightly tapered and the taper of the side walls of the screw slots slightlyincreased, to cooperate with the taper of the sidewalls of the wings of the driver. e

The same reference numerals throughout the several views indicate the same parts;- In the type of screw and screw driver heretofore commonly employed, the screw has a slot milled or otherwise formed diametrically from side to side through the top of the head, and the driver bit has a transverse and substantially straight edge for engagement in the screw slot. It is a matter of common that such construction embodies serious defects, such as the fact that it is difficult under some circumstances to quickly engage the driver edge inthe slot, and there is gaged, for it to slide longitudinally out of the slot and mar the work. If the driver is tipped a little out of the axis of thescrew, its edge tends to rise out of one end of the screw slot and act as a cam to disengage the driver altogether and, in so. doing, burring and injuring the screw. There is, furthermore, very little control by the driver of the position of the screw. The slot traversing the full width of the head, has seriously weakened it and resulted in frequent splitting ofi of one-half the head. While various modified constructions have been suggested to overcome such defects, they have been only pare tially successful and open it is the purpose of the present invention to provide a successful solution of such difiiculties.

This application is a division of my cop-ending applicationresulting in Patent No. 2,058,197, issued October 20, 1936, for an improvement in Screws. l

In the embodiment of the invention herein shown, by way of illustration, there is formed in the head of the screw 2. driving recess comprising as one of its components, a relatively small socket-like opening as shown extending down the screw axis from the face or top of the head to about the junction of the head with the shank of the screw, so that the socket lies substantially in the larger head portion without weakening the shank. This socket preferably has outwardly or concavely curved walls and may be generally round in cross-sectional shape, although it is recognized that various other shapes may be employed to afiord a socket-like opening. It is slightly inwardly as shown to decrease m width toward its bottom, and it is, in fact, preferred to use, and the drawing shows, a substantially conical socket it, to be closely experience in the art,

a tendency, when en'- to other objections, and

engaged by a corresponding tapered body portion on the driver bit, as hereinafter described,'

and serving to locate and hold the driver accurately and securely centered in the screw recess.

and extending outwardly from the tapered sides of the socket for engagement by corresponding wings on the driver bit. Such slots are shown at IT, each having sidewalls 3 which are spaced apart and preferably parallel with each other in planes transverse to the axis of the screw, as shown in Figs. 4 and 8. These side walls l8, however, are preferably inclined slightly toward each other in a downward direction as shown at IQ, for a purpose hereafter described. The slot side walls [8 are joined by an outer end surface 'or wall 20 which is preferably inclined outwardly and upwardly from adjacent the bottom of socket l6 as indicated at 2|, to the top of the driving recess at 22, terminating at a substantial distance inwardly from the periphery of the head. While this outer slot wall may have various forms, it is preferred to employ a smoothly or continuously curved, shape, so as to avoid sharp corners which might tend to pry the driver out of the recess in the screw when tipped out of' the screw axis. Preferably also the outer slot wall 29 is curved in a direction which is first mainly outwardly as at 23, and then mainly upwardly as at 24, to afford substantial lateral width for the slot adjacent its bottom and to generally parallel the outer wall of the screw head without approaching it near enough to seriously weaken the head.

It is preferred to employ, and the drawing shows the slots l1 extending outwardly from two opposite'sides only of socket it, rather than a larger number of slots which would tend to excessive displacement of metal and weakening of the head of the screw, particularly in the area between adjacent slots to which the turning force is mainly applied. Such a construction also permits the use of slots of substantial lateral width .continued close to the axis-of the screw, as a further element of strength, and, of course such a construction is easier to manufacture than one having a larger number of slots.

The dotted outline 25 in Fig. 2 of a screw of smaller size, indicates that by using sockets l6 of the same size in a range of screws of different size, and forming the slots ll of greater or less lateral extent to correspond with the size of the screws, such range of screws of different sizes may be used with a single driver bit which merely enters to a greater or less depth as the size of the screw and its driving recess may require.

To facilitate the engagement of the driver bit, the top or face of the screw head is preferably dished somewhat inwardly as indicated at 28, such shape being carried slightly beyond the outer ends of the slots IT, as shown, but terminated as-indicated by the circle 21, at some distance from the periphery of the screw head. This dished shape affords a self-centering action between the screw and driver, causing the latter to travel toward the center of the screw and its driving recess. Furthermore, it is a common practice to enter the screw in the work by striking its head with a hammer and the dished shape described prevents the hammer from striking the portion of the head in which the driving recess is formed, to protect it from the injury which is frequently caused by such hammering the ordinary screw. The termination of the dish shape in spaced relation with the periphery of the head also tends to protect the peripheral edge from similar injury.

The driver is designated generally by the reference numeral 28. The shank of the driver is indicated at 2841 as terminating in a bit comprising generally a central body portion or spine 29 for engagement in the screw socket l6, and opposed wings 30 for engagement in the screw slots IT. The body portion 29 conforms closely to the shape of the screw socket "5, being in the present instancesubstantially conical in shape and smaller at its outer end 3| as shown. The opposite sides of the body 29 may be formed with a relatively fine longitudinal fluting, or other roughening 32, audit will be understood that this body of the driver bit is adapted to be inserted longitudinally in and to closely fit socket [8 of the screw, as shown, the toughening 32 being intended to assist the bit in tightly engaging the screw to drive it and also so that a screw may be placed on and carried by the bit as a holder for locating and starting the screw relative to the work. The extremity of the driver body 29 is preferably rounded as shown to form an extended blunt point adapted to slide down the dished head of the screw into its driving recess and socket. The bottom of the screw socket I6 is extended below the bottoms of the slots I! to receive and clear this extension at the end of the driver body 29 as shown in the drawing.

The driver wings 30 each have opposite faces or walls which are preferably parallel with each other, and so spaced apart as to afford the desired thickness and strength. These wing walls are joined by an outer end surface or wall 33 inclined or curved from a point adjacent the lower end of the body in a direction first mainly outwardly and then mainly upwardly relative to the body 29, as shown, to conform generally with'the shape of the outer end surfaces or walls 20 of the screw slots I I. The outer end surfaces or walls 33 of the driver wings are continued outwardly and upwardly to a point beyond the top of the head of the largest screw with'which the driver is normally intended to be used, or at least far enough to afford the desired lateral extent and driving force, beyond which the outer wall of the wing is continued parallel with the driver axis until it joins its shank at the top of the body 29. The outer walls 33 of the wings of the driver bit are so shaped and dimensioned as to be of less length laterally in any given transverse plane, than the outer walls 20 of the screw slots IT, with the result that when the driver is fully seated in the screw, a clearance is provided between such outer walls of the wings and slots, respectively. as shown in Fig. 2. Such clearance not only avoids interference of these outer walls with each other during the driving operation. but also permits of some tipping of the driver during engagement with the screw without such contact of these outer walls as might tend to cam the driver out of the screw recess. The present invention .thus overcomes the disadvantages of the screw and driver heretofore in use, namely, the tendency of the shoulders formed by the ends of the transverse driver edge, to cam the driver edge out of the screw slot, whenever the driver is slightly tilted. The relatively deep seating of the present driver bit in the screw recess also aids in overcoming the same difiiculty. v

The driver and screw are specially coordinated V 2,160,244 in shape to bring about concentration of the driving engagement and pressure belowthe tops of the slots in the screws. To this end, the side walls 30 of each driver wing are preferably made parallel, as stated and as indicated in Fig. 7, andthe walls It of the screw slot l1 are tapered slightly away from each other in an upward direction, so

that when the bit is inserted in the screw recess, these wall surfaces of the driver wings first engage closely the bottoms of' the walls of the slots, as at 3t, Fig. 7, leaving a slight clearance between the adjacent walls at the top of the slots as at 35,"Fig. '7. If such walls ofeach driver wing be tapered toward each other in the direction of the driver point, as shown in themodiiication, Fig. 9, then the side walls of each slot in the screw may be given a greater degree of taper as.

shown at 69a in Fig. 9 tomaintain the same condition of initial engagement adjacent the bottoms of the walls of the slots in the screw and clearance adjacent their tops.

As the turning pressure is applied, the driver wings first press against the bottoms of the side walls of the screw slots without engagement of the driver wings with the sides of the slots at 'the top or face of the screw head. Should the driving force be sufficient to cause the parts to yield, orthe softer metal of the screw to be de formed, then the outer edges of the driver wings are brought progressively into more extended engagement with the walls of the screw slots, beginning as stated. adjacent their bottoms and working progressively upwardly, thus tending to equalize the pressure from bottom to top of the Wings and slots, and if such contact of the driver Wing's is extended as far as the tops of the side walls, as indicated at 36 in Fig, 8, the extent of for engagement and cooperation by adriver bit,

surface engagement is amply sufidcient to prevent any burring or other defacement of the tops of the slots at the face of the screw. Consequently, the driver receiving recess'at the face of the screw maintains its normal and efficient shape through long continued usage of the screw and the application oi severe turning force.

As well understood in. thev art, screws of the present type are commonly manufactured of metals of a relatively soft nature, such as soft steel, brass, and the like, and a driving recess of.

the above described character maybe readiiy forged in the head by appropriate dies and standard manufacturing, methods. The driver bit is ofa character also which may be readily formed as by means of an ordinary and inexpensive drop forging operation, although, of course, other manufacturing methods may be employed in part or in whole.

in operation, the bluntly rounded end or key 33 of the driver is applied to the. dished face of the screw head, either before or after the screw is started in the work. The bit key, sliding down the incline, in a self-centering action, readily finds the screw socket, or one of the screw slots which it follows into thesocket. The bit turns until its wings register with and enter the slots in the screw, as the body of the bit enters the screw socket. Such engagement may be partially made with the driver at an inclination to the axis of the screw which, if not excessive, does not the wings of the bit first engaging with the bottoms of the walls of the slots in the screw, as indicated in Fig. '7. In this relation the driver takes effective grip upon and control over the screw and may be used to direct and maintain. it in the desired direction relative to the work. The turning force is first applied, as described, at the bottoms'of the side walls of the screw slots and thence progressively upwardly toward the face of the screw head, as the degree of the force may require. The substantial length of engagement of said parts affords ample bearing surface for the transmission of such forces, without deforming the screw recess at the face of the head or decreasing its continued efficiency for cooperation with the driver. Such secure engagement-of the driver and screw reduces the force necessary to hold the parts in cooperation. The rapidity and certainty with which they may be engaged make it possible to effectively operate the driver by suitable power driven means.

I The driver bit is of such a'nature that it may be easily manufactured by standard methods in a strong and durable form,,of the usual hard steel, and a single driver is adapted for use with a wide rangeof sizes of screws.

it will thus be seen that the invention accomplishes the objects to be attained, and it is to be understoodthat the preferred embodiments described above are intended by way of illustration and not by way of limitation and that various modifications may be resorted. to within the prin-.

wardly from adjacent the bottom of the socket and terminating inwardly of the periphery of the head with the side walls of the slots slightly convergingtoward the bottoms thereof, said driver having a substantially conical spine for operation in said socket, the outer wall surfaces of said spine having roughened portions formed thereon for cooperation with the walls of said socket to assist in the driving of the screw and retention thereof on the spine whereby the driver may be used as a holder for applying the screw to the work, said driver having wings on opposite sides of the spinefor cooperation with the side walls of the slots to insure efiective driving engagement between the wings and said walls, said wings being adapted to fit the slots more closely adjacent their bottoms than at their tops.

2. A driver for a screw of the character having a head formed with a driving recess comopposite side walls tapered slightly inwardly and having'bottoms inclined obliquely outwardly and upwardly from adjacent the bottoms of 0pposite sides'of said socket toward the top of said head inwardly of the periphery thereof, said driver comprising a bit having an elongated, slightly tapered, substantially conical spine and driving wings the outer edges of which are inclined obliquely outwardly and upwardly from adjacent the bottoms of opposite sides of said spine below said taper thereof for driving en-' gagement in said slots, said spine having a diameter which is relatively small in relation to its length and to the diameter of the screw and formed to seat with a tapered fit in said socket, said wings having opposite faces which are substantially parallel to one another for engagement with said tapered side walls of said slots primarily adjacent the bottoms of said slots.

3. A driver for screws having a head formed with a central, elongated socket extending with an inwardly converging taper adjacent the bottom of the head and having a pair of oppositely disposed driving slots each formed with inwardly converging side walls and with a marginal wall inclined outwardly and upwardly from adjacent the bottom of said socket and terminating inwardly of the periphery of said head, said driver having an elongated spine tapered to fit said socket, and oppositely disposed driving wings with side walls substantially parallel with one another and with marginal edges inclined obliquely outwardly and upwardly from said spine below the taper thereof for operation in said screw slots by engagement terminating in spaced relation with said marginal walls of said screw slots, whereby said driver is seated and bottomed in a screw by the tapered seating of said spine in said socket with said wing edges spaced from said marginal slot walls of the screw, and whereby said wings have driving engagement with said slot side walls adjacent the bottoms thereof.

4. A driver for a screw of the character having ahead formed with a driving recess comprising a socket with a slight inward taper and a pair of driving slots having bottoms inclined obliquely outwardly and upwardly from adjacent the bottoms of opposite sides of said socket toward the top of said head inwardly of the periphery thereof, said driver comprising a bit having a screw centering and holding spine, and driving wings the outer edges of which are inclined obliquely outwardly and upwardly from adjacent the bottoms of opposite sides of said spine, for driving engagement with the sides of said slots, said spine having a thickness which is relatively small in relation to its length and to the lateral extent of said wings and having a slight inward taper extending to a substantial distance above-the bottoms of said wings for seating saidspine with a tapered fit in said tapered screw socket.

5. A driver for a screw of the character having a head formed with a driving recess comprising a socket with a. slight inward taper and a pair of driving slots having bottoms inclined obliquely outwardly and upwardly from adjacent the bottoms of opposite sides of said-socket toward the top of said head'inwardly of the periphery thereof, said driver comprising a bit having an elongated screw holding spine, and driving wings the outer edges of which are inclined obliquely outwardly and upwardly from adjacent the bottoms of opposite sides of said spine, said spine being thin in relation to its length and to the lateral extent of said wings and having a slight inward taper extending to a substantial distance above the bottoms of said wings, for seating said driver in said screw by the tapered fit of said spine in said screw socket and for driving said screw by engagement of the sides of said wings with the sides of said screw slots.

6. A driverfor a screw of the character having a head formed with a driving recess comprising a socket with a slight inward taper and a pair of driving slots having bottoms inclined obliquely outwardly and upwardly from adjacent the bottoms of opposite sides of said socket toward the top of said head inwardly of the periphery thereof, said driver comprising a bit having an elongated, substantially conical, screw holding spine, and driving wings the outer edges of which are inclined obliquely outwardly and upwardly from adjacent the bottoms of opposite sides of said spine, said spine being thin in relation to its length and to the lateral extent of said wings and having a slight inward taper extending to a substantial distance above the bottoms of said wings for seating said driver in said screw by the tapered fit of said spine in said screw socket and for driving said screw by en-v gagement of the sides of.said wings with the sides of said screw slots.

7. A driver for screws having a head formed with a central, elongated socket extending with an inwardly converging taper adjacent the bottom of the head and having a pair of oppositely disposed driving slots, each formed with a marginal wall inclined outwardly and upwardly from adjacent the bottom of said socket and terminating inwardly of the periphery of said head, said driver having an elongated spine tapered to fit said socket and oppositely disposed driving wings with marginal edges inclined obliquely outwardly and upwardly from a point on said spine substantially below the tapered portion of said spine for engagement in said screw slots, said wing edges being terminated in spaced relation with said marginal walls of said screw slots, whereby said driver is seated and bottomed in a screw by the tapered fitting of said spine in said socket with said wing edges spaced from said marginal slot walls of the screw.

8. A driver for screws having a head formed with a central, elongated, substantially conical socket extending with an inwardly converging taper adjacent the bottom of the head and having a pair of oppositely disposed driving slots each formed with inwardly converging side walls and with a marginal wall inclined obliquely outwardly and upwardly from adjacent the bottom of said socket and terminating inwardly of the periphery of said head, said driver having an elongated, substantially conical spine tapered to fit said socket, and oppositely disposed driving wings with side walls substantially parallel with one another and with marginal edges curved obliquely outwardly and upwardly from said spine below the taper thereof for operation in said screw slotsby engagement terminating in spaced relation with said marginal walls of said screw slots, whereby said driver is seated and bottomed in a screw by the tapered seating of said spine in said socket with said wing edges spaced from said marginal slot'walls of the screw.

MAXWELL A. WEST. 

